gh-103636: issue warning for deprecated calendar constants

Lib/calendar.py

@@ -10,6 +10,7 @@
 from enum import IntEnum, global_enum
 import locale as _locale
 from itertools import repeat
+import warnings
 
 __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
            "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
@@ -41,6 +42,18 @@ def __str__(self):
         return "bad weekday number %r; must be 0 (Monday) to 6 (Sunday)" % self.weekday
 
 
+def __getattr__(name):
+    if name in ['January','February']:
+        warnings.warn(f"The '{name}' attribute is going to be deprecated use '{name.upper()}' instead",
+                        DeprecationWarning,
+                        stacklevel=2)
+        if name == 'January':
+            return JANUARY
+        else:
+            return FEBRUARY
+
+    raise AttributeError(f"module {__name__} has no attribute {name}")
+
 # Constants for months
 @global_enum
 class Month(IntEnum):
@@ -71,6 +84,7 @@ class Day(IntEnum):
 
 
 
+
 # Number of days per month (except for February in leap years)
 mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
 

Lib/test/test_calendar.py

@@ -8,6 +8,7 @@
 import sys
 import datetime
 import os
+import warnings
 
 # From https://en.wikipedia.org/wiki/Leap_year_starting_on_Saturday
 result_0_02_text = """\
@@ -490,6 +491,16 @@ def test_format(self):
             self.assertEqual(out.getvalue().strip(), "1   2   3")
 
 class CalendarTestCase(unittest.TestCase):
+
+    def test_deprecation_warning(self):
+        with warnings.catch_warnings(record=True) as w:
+            # Access the deprecated attribute
+            _ = calendar.January
+            # Check that a DeprecationWarning was issued
+            self.assertEqual(len(w), 1)
+            self.assertEqual(w[0].category, DeprecationWarning)
+            self.assertIn("The 'January' attribute is going to be deprecated use 'JANUARY' instead", str(w[0].message))
+
     def test_isleap(self):
         # Make sure that the return is right for a few years, and
         # ensure that the return values are 1 or 0, not just true or